在java中顯示問題，找不到符號錯誤

Question

繼續收到這些找不到符號錯誤。我知道它涉及的圖片類和它的方法，但我知道他們在那裏，但我的編譯器無法識別它們。有任何想法嗎？發現

 import java.awt.Color; 
    import java.awt.Graphics; 

    public class DispTest 
    { 

     private Picture display; 
     private Graphics graphics; 

     public DispTest() 
     { 
     display = new Picture(500,500); 
     graphics = display.getGraphics(); 
     for(int x = 0; x < display.getWidth(); x++) { 
      for(int y = 0; y < display.getHeight(); y++) { 
      display.getPixel(x,y).setColor(new Color(123,204,246)); 
      if((x > 0 && x % 50 == 0) || (y > 0 && y % 50 == 0)) 
      display.getPixel(x,y).setColor(new Color(44,72,39)); 
      } 
     } 

     graphics.setColor(new Color(44,72,39)); 
      for(int x = 10; x < display.getWidth(); x += 50) 
      for(int y = 10; y < display.getHeight(); y += 50) 
       graphics.drawOval(x,y,30,30); 
      display.show(); 
     } 


     public static void main(String [] args) 
     { 
      DispTest dt = new DispTest(); 

     } 
    } 

5個錯誤：

File: C:\Users\Andrew\SoftwareDevelopment\DispTest.java [line: 22] 
Error: cannot find symbol 
    symbol: method getGraphics() 
    location: variable display of type Picture 
File: C:\Users\Andrew\SoftwareDevelopment\DispTest.java [line: 25] 
Error: cannot find symbol 
    symbol: method getPixel(int,int) 
    location: variable display of type Picture 
File: C:\Users\Andrew\SoftwareDevelopment\DispTest.java [line: 27] 
Error: cannot find symbol 
    symbol: method getPixel(int,int) 
    location: variable display of type Picture 
File: C:\Users\Andrew\SoftwareDevelopment\DispTest.java [line: 32] 
Error: cannot find symbol 
    symbol: method getWidth() 
    location: variable display of type Picture 
File: C:\Users\Andrew\SoftwareDevelopment\DispTest.java [line: 33] 
Error: cannot find symbol 
    symbol: method getHeight() 
    location: variable display of type Picture 

Answer 1

刪除您.class文件，並重新編譯代碼。當您的.class文件來自舊版本的源文件時，會發生此錯誤。

Answer 2

是不是Picture應該是Image類，import java.awt.Image;增加在你的課上？在這種情況下，IDE（Eclipse，Netbeans）會幫助你。

所以，你可以有：

// import 
import java.awt.Image; 
import java.awt.image.BufferedImage; 

... 

// declaration 
private Image display; 

... 

// instantiation, feel free to choose your third argument from http://docs.oracle.com/javase/6/docs/api/java/awt/image/BufferedImage.html 
display = new BufferedImage(500, 500, BufferedImage.TYPE_INT_RGB);